Ericsson ECN330, User Manual

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Configuring the ECN330-switch
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that hello messages also contain the DR priority of the router
sending the message.
• Hello Hold Time (seconds) – Sets the timer that detects whether a
neighbor router is still alive and sending hello messages.
(Range: 1-65535; Default 3.5 times the hello interval)
• The hello-holdtime indicates how many seconds the router holds an
entry for a neighbor that has stopped sending hello messages.
• The hello-holdtime should be included in each hello message
received from a neighbor. Routers on the same subnet may
therefore have different hello-holdtimes.
• If the hello interval is set at the default value of 30 seconds, then the
default hello-holdtime is 105 seconds. If the hello-holdtime has not
been configured, then every time the hello interval is updated, the
hello-holdtime is automatically updated. However, if the hello-
holdtime has been configured, then it will not be updated when the
hello interval changes.
• If a value is set for the hello-holdtime that is less than the hello
interval, the command will fail. Also, if the hello-holdtime is already
configured, and the hello interval is set to a value longer than the
hello-holdtime, the command will fail.
• DR Priority (0-4294967294) – Sets the priority advertised by a router
when bidding to become the Designated Router (DR).
(Range: 0-4294967294; Default: 1)
• More than one PIM-SM router may be connected an Ethernet or
other shared-media LAN. If multicast hosts are directly connected
to the LAN, then only one of these routers is elected as the DR, and
acts on behalf of these hosts, sending periodic Join/Prune
messages toward a group-specific RP for each group. A single DR
is elected per interface (LAN or otherwise) using a simple election
process.
• The router with the highest priority configured on an interface is
elected as the DR. If more than one router attached to this interface
uses the same priority, then the router with the highest IP address
is elected to serve as the DR.
• If a router does not advertise a priority in its hello messages, it is
assumed to have the highest priority and is elected as the DR. If
more than one router is not advertising its priority, then the router
with the highest IP address is elected to server as the DR.